The present invention refers to a method for the preparation of a concentrated inoculating composition for legumes, preferably soybeans, alfalfa and beans and the inoculating composition obtained with such a method.
It is known in the art that, under certain conditions, leguminous plants fix nitrogen directly from the air and convert it to certain nitrogenated organic compounds and thus supply nitrogen to the plant for protein synthesis and also enrich the soil, also leaving nitrogenated nutrients for later crops. This fixation is caused by the bacteria named Rhizobium Japonicum or Bradyrhizobium Japonicum existing symbiotically with the plant forming infective nodules in the neck of the root. Nitrogen fixation is a function of the number of infective nodules in the neck of the root, and thus counting the nodules can be used to quantify the efficiency of the inoculant that is used. Therefore, greater nitrogen fixation is achieved with the inoculants containing the highest number of Bradyrhizobium bacteria and, above all, their infectivity.
The inoculants per se were modified in their characteristics from solid substrates such as peat, vermiculite, perlite, charcoal, etc. as carriers of Bradyrhizobium in liquids as the majority of those that are now on the market.
Since the appearance of liquid inoculants, the first problem to solve was to achieve a higher survival rate of the Bradyrhizobium because the period of effectiveness increases as a function of the survival thereof in the inoculant. At an early stage, the viability of one of the inoculants was one month, the majority now lasting as much as eighteen months and some even two years.
The advantage of the liquid inoculants was the greater quantity of bacteria containing +/−1.00×1010/ml of Bradyrhizobium and the practicality of their use. On the other hand, they exhibited the disadvantage of greater fragility and hence less viability of their Bradyrhizobium bacteria in the face of attacks by products such as fungicide as well as the dryness of the environment, temperature, pH of the soil, etc.
Solving this problem started with the addition of previously sterilized and neutralized ground peat to the culture medium already prepared with a 1×1010 concentration of Rhizobium Japonicum, a mixture made prior to the packaging of the culture medium.
Although the addition of the previously sterilized and neutralized ground peat to the culture already prepared with a 1×1010 concentration of Rhizobium Japonicum improved the viability of the Rhizobium Japonicum bacteria facing the attacks mentioned, which was manifested by improved nodulation, the acidity of the peat itself and its different pH versus the medium in which it was incorporated did not allow an optimum absorption of the Rhizobium Japonicum bacteria. These results were amply overcome by the invention which is submitted for patenting. This invention solves the problem, achieving greater protection, resistance and viability of the Rhizobium Japonicum bacteria facing the attacks previously described and achieving a greater multiplication of the Rhizobium Japonicum bacteria contained in the peat, as will be explained in this specification.
For this purpose, powdered maltose and liquid maltose and lactose saccharides as well as a fungicide called potassium sorbate are added to the culture medium forming the concentrated inoculating composition. The result of all of this is a greater viability of the Rhizobium Japonicum bacteria compared with the viability that the bacteria would have without these additives to the culture medium.
In turn, if peat is simultaneously added with the other ingredients to the general use culture medium, the bacteria will have greater resistance to the attacks mentioned and greater multiplication thereof. This is because of a greater degree of impregnation of the bacteria in the peat incorporating it once the culture medium is finished, there being better neutralization of the acidity of the peat which is combined with the culture medium and takes on the same on the same pH as the latter. It thereby acquires a greater capacity for absorbing bacteria because, at the stabilization temperature, the peat becomes more spongy and thus more porous, thus promoting greater interaction with the bacteria.